In general, all other properties being the same, light-weight fabrics normally provide a number of advantages over heavier fabrics. Thus, lighter fabrics are easier and less expensive to ship and handle than heavy fabrics, and are additionally less expensive because of a lower raw material content. Consequently, the use of lighter weight fabrics results in final products which are less expensive due to a lesser quantity of raw material, and which are easier and less expensive to ship and handle than products produced from heavier fabrics.
A large variety of agricultural fabrics are produced of various sizes and types to serve a large variety of particular needs, such as poultry curtains, shade cloth, ground cover, nursery squares, seed cover, etc. It would be desirable to be able to produce such products having the same degree of coverage, but with a better yield, i.e. a lower weight of product per unit area of coverage. The same is true with regard to fabrics for the home furnishing market, including upholstery fabrics, drapes, outdoor furniture fabrics, etc., where key features include coverage per unit weight of fiber, and flame retardency.
Additionally, many fabric applications require a fabric which, while flexible, will not present any sharp edges which can injure or damage a delicate object resting thereagainst. For example, the packaging of potatoes presents a serious and long existing problem because of the sensitivity and easy abradability of potato skins, especially when freshly picked. Both producer and consumer bags for potatoes, constructed of open mesh synthetic fiber or ribbon fabrics, have been tried unsuccessfully; the fibers of the synthetic fabric tend to cut or abrade the sensitive skin of the potato, this being a particularly serious problem in producer bags used by the farmer before the potato skin has "cured". Consequentiy, consumer and producer bags for potatoes are conventionally formed of paper or coated paper, which is quite expensive. Some producer bags are formed from jute which is also expensive, and which sometimes cuts the uncured potato skins and sometimes causes rotting of the potatoes. Some consumer potato bags are formed of plastic film with holes cut therein, but these tend to cause undue rotting in spite of the ventillation holes which are cut through the film. Consequently, a great need exists for an improved potato bag, for use at both the producer and consumer levels, which does not cause the aforementioned problems.
While the packing of other types of produce does not present the severity of the problem occasioned by the bagging of potatoes, there is nevertheless a need for an improved general purpose open-mesh produce bag which is sturdy and reliable, does not promote rotting of the produce packaged therewithin, and which is of 1ighter weight and therefore less expensive than conventional open-mesh produce bags.
Tightly woven synthetic fiber fabric in the form of liner fabric is often used as a curing blanket during the processing of rubber, and this type of fabric is reused as long as it lasts. Its primary function is to support the rubber while offering wrinkle resistance during the curing of the rubber. While one of the necessities of such a curing blanket is that it must offer good release properties of the cured rubber from the fabric, in practice the conventional woven fabrics inevitably have an excess of open spaces into which the raw rubber penetrates, thus causing release characteristics which are not as good as desirable. Consequently, it has been found much more suitable to use flat film rather than liner fabric as a rubber curing blanket even though flat films are not reusable and, consequently, are much more expensive. Therefore, a need exists in the rubber industry for an improved curing blanket which will combine the best properties of flat film and woven liner blankets.
In the carpet industry, most carpet today is made by tufting. Tufted carpet requires a fabric backing through which face yarns are inserted. The tufted carpets normally use a backing fabric made of interwoven fibers of large diameter or of tapes or ribbons (see U.S. Pat. No. 3,110,905) so that the tufted facing yarns may be passed through the large diameters of fibers or ribbons. In automobile and airplane carpets, fabric weight is of especial importance in increasing fuel economy. The backing fabrics should also be flame resistant and are normally required to be made of relatively heavy plastics such as nylons and polyesters because these are more resistant to heat than polyolefins backing fabrics used for conventional tufted carpeting. There is a need in this industry to provide a lighter weight carpet backing, especially for use in the manufacture of automotive and airplane carpeting, which is flame resistant and formed of relatively high melting point, heavy and expensive polymers such as nylons and polyesters.
Filter fabrics normally used today are woven from monofilaments and/or multifilaments and are finished by shrinking methods or calendering to control the equivalent opening size (E.O.S.) or porosity. Shrinking and calendering both require substantial amounts of time and expense. If expensive and time consuming finishing steps such as shrinking and calendering were eliminated or reduced, the production of filter fabrics would be made more efficient and less costly.
It has been pointed out above that fabrics woven of tapes or ribbons are known, e.g. such as for carpet backing for tufted carpets as disclosed in Rhodes U.S. Pat. No. 3,110,905. Mats or the like have also been made from woven ribbons or tapes, noting Kallmann U.S. Pat. No. 2,381,061 Wallach U.S. Pat. No. 1,995,696; Bowser U.S. Pat. No. 1,471,376; Mauran U.S. Pat. No. 562,635 and Stedman U.S. Pat. No. 2,354,435. While these patents show the production of very uniform products, in practice it is exceedingly difficult, if not impossible, to weave ribbons without causing twists, especially for the fill. It is even difficult to make the warp without twist, but it is virtually impossible, due to the inherent nature of the weaving process and especially the removal of the fill yarn from its package during weaving, to make a fabric with an untwisteo ribbon fill, short of taking heroic and very time consuming and costly steps.
Conventional fabric of course uses multifilament yarns and sometimes monofilament yarns. Whatever yarns are used, twisting is almost always carried out as a preliminary step in order to provide necessary strength and to prevent the yarns from falling apart. Of course, this constitutes an additional processing step which increases the cost of the final product.
Various types of hollow and semi-hollow synthetic textile fibers have been proposed, such as those mentioned in the patents listed at column 2, lines 24-39 of the Ward et al U.S. Pat. No. 307,478. These are invariably of irregular configuration both radially and from point-to-point along the length thereof. In addition, such synthetic textile fibers are almost always used to form multifilament yarns before being woven into fabric. As a result, the yarns have a tendency to bulkiness, simulating natural fiber yarns as normally desired by the various patentees, but these synthetic yarns are anything but uniform. Also, as mentioned above, the formation of yarns requires a twisting step which adds to the cost.
Relatively uniform hollow brush bristles are also known, e.g. U.S. Pat. Nos. 3,121,040; 3,251,729 and 3,216,033. Insofar as is known, sucn bristles have never been used for weaving fabric, nor has it been contemplated that fabric woven from such bristles would have any particular use, let along improved properties for certain uses.